that's over 99% effective at preventing pregnancy for as long as you want, for up to five years. then again, i'm not sure i want to wait. don't use mirena if you have a pelvic infection, get infections easily or have certain cancers. less than 1% of users get a serious infection called pelvic inflammatory disease. if you have persistent pelvic or stomach pain, or if mirena comes out, tell your healthcare provider. if it comes out, use back-up birth control. mirena may attach to or go through the uterine wall and cause other problems. although uncommon, pregnancy while using mirena can be life threatening and may result in loss of pregnancy or fertility. ovarian cysts may occur, but usually disappear. bleeding and spotting may increase in the first few months and continue to be irregular. periods over time may become shorter, lighter, or even stop. mirena does not protect against hiv or stds. oh, i can wait a little longer. ask about mirena. when you have time. did you know ? if you choose mirena to prevent pregnancy, it's also approved to treat heavy periods.